Carbon pile regulator



Nov. 1, 1949 w. 1. RADY ET AL 2,486,978

CARBON FILE REGULATOR Filed Aug. 25, 1947 3 SheetsSheet l INVENTORS will!!!" J. Raw m BY lYMnN A RI.

Tun! ATTORNEYS Nov. 1, 1949 w. J. RADY ET AL 2,486,978

CARBON FILE REGULATOR Filed Aug. 23, 1947 3 Sheets-Sheet 2 A iii. 1.... 17

Z43 INVENTORS 24: Wil i/w RAnv mvn 249- v 2: BY lvmmv A. Rice 240 f Ja 9A Tut/ ATTORN EYS NOV. 1, 1949 w, J, A ETAL 2,486,978

' CARBON FILE REGULATOR Filed Aug. 25, 1947 3 Sheets-Sheet 3 INVENTORS WI/l/AM J2 Rqnv AND BY LY/ww A. R/ct.

THt/R ATTORNEYS Patented Nov. 1, 1949 CARBON PILE REGULATOR William J. Rady and Lyman A. Rice, Anderson, Ind, assignors to General Motors Corporation, Detroit, Mich a corporation of Delaware Application August 23, 1947, Serial No. 770,268

This invention relates to improvements in electric regulators of the carbon pile type and more particularly to carbon pile regulators such as are used on automotive vehicles wherein the generator is employed to charge the storage battery.

An object of the present invention is to provide a compact, easily adjusted and highly effective automatic regulator for varying the resistance in. response to the flow of current through a certain circuit.

Another object of the present invention is to provide spring means for controlling the pressure exerted on a pile of carbon discs and opposing the force of the magnet which is so constructed and arranged that the force exerted thereby increases at the same rate as the force exerted by the magnet increases upon decrease in the air gap.

Another object is to provide resistance compression means including a magnetically rockable member and a movable contactor operatively connected with the rockable member and interposed between the rockable member and one end of the resistance which will vary the compression of the resistance in response to relatively small movements of the rockable member.

Another object of the invention is to provide a radiator for a carbon pile regulator which will dissipate heat from the carbon pile.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a top plan view of a voltage regulator.

Fig. 2 is a sectional view taken in line 2--2 of Fig. 1.

Fig. 3 is a bottom plan view of the regulator shown in Fig. 1.

Fig. 4 is a side view looking in the direction of arrow 4 of Fig. 2.

Fig. 5 is a sectional view on line 55 of Fig. 1.

Fig. 5A is a modified form of the spring structure shown in Fig. 5.

6 is a sectional view on line 6-5 of Fig. 2.

Fig. 7 is a sectional view on line ll of Fig. 2.

Fig. 8 is a plan view of a current regulator.

Fig. 9 is a sectional view taken on line 9-9 of Fig. 8.

Fig. 9A is a sectional view showing a modified construction and arrangement of carbon discs.

Fig. 10 is a plan View of cooling means associated with the regulators in accordance with the present improvements.

12 Claims. (Cl. 201-51) Fig. 11 is a sectional view taken on line H of Fig. 10.

Fig. 12 is a wiring diagram of a generator regulating system embodying the present invention and shows particularly the arrangement of the regulators and other electrical instruments with which the generator and a battery are connected.

Referring to Figs. 1 to 7, inclusive, a detail structure of a voltage regulator 20 will be described. The voltage regulator comprises a housing 2|, of good thermal conductivity, such as aluminum having a through opening 22 to receive a refractory insulatin tube or sleeve 23 which houses a compressible resistance such as a stack of carbon discs 24.

The housing 2| supports a subassembly including a metallic U-shaped mounting bracket 25 and a metallic U-shaped frame 26 as shown in Fig. 6. In this construction arms 27 of the frame 26 are secured to arms 23 of the bracket by a series of rivets 29. Parts 25 and 26 are magnetizable. The arms 2% of the mounting bracket 25 are provided with ears 30 which are bent at an angle to the normal plate of arms 28 and toward each other. Plates 3! are attached to cars 30 in any suitable manner, as by spot-welding, in order to provide extra thickness. The ear and plates are tapped to receive the threaded ends of screws 32 which attach the fram 25 to the base 2|.

The yoke 35 of the frame 26 is provided with an openin for receiving a reduced portion 36 of a magnetizable core 31. The core 3'! is attached to the yoke 35 by riveting over the reduced portion 35 against a magnetizable washer 88. The core 3? supports a coil assembly including a winding to of fine wire about a brass tube 4! surrounded by a sleeve of insulating material. The ends of the tube 4! are bent radially outward against respective insulating washers 12 located around the tube and bearing against an insulating sleeve 42a. A metallic stop washer 43 is press fitted over the free end of core 31 to hold the coil assembly thereon. The coil assembly is urged against the stop washer 43 by a coil spring or resilient member 44 disposed between the innermost washer 42 and the yoke 35.

The armature assembly for the regulator comprises a U-shaped hinge support 50 (Figs. 2 and '7) having a yoke 5| provided with an opening 52. The side arms 53 of the hinge support are provided with elongated openings 54, (Figs. 4 and '7) to permit adjustment of the support 58 relative to the frame 26. Screws pass through the open' ings 54 and have threaded engagement with tapped holes in the frame 26. The screws 55 will,

3 when tightened, secure the hinge support 50 to the frame 25 in the desired position or adjustment. The hinge support 50 is provided with an car 55 (Fig. 2) bent at an angle from the normal plane of the yoke.

An armature 66 is hingedly connected with the ear 56 by a flexible bi-metal strap iii to compen sate for change in temperature. One end of the strap 6i is secured to the armature 60 by rivets 62. The other end of the strap BI is provided with elongated openings to receive screws 64, which pass through the openings and have threaded engagement with tapped holes in the ear 56. When the screws 65 are tightened they will secure the strap to the ear in the desired position of adjustment.

A rockable U-shaped arm it is attached to the armature B5. The arm it includes a yoke II provided with a tapped opening 12 and a plain opening "I3 and having side branches M provided with spaced openings I5. The side branches are provided with ears It bent toward each other and attached to the armature 60. Certain of the rivets 62 which secure the strap iii to the armature also pass through the ears I6 and are peened over against the outer surface of the ears i and thus assist in securing the ears T6 to the armature 69. Ears I6 are attached to armature 68 also by screws I? which are screwed into armature 55.

Referring to Fig. 4, it will be noted that the spaced openings '35 are larger in dimensions than the head of the screws 55 thus permitting a tool, such as a screwdriver, to loosen the screws 55 so that hinge support 58 can be adjusted relative to the arms 25 to vary the gap between the armature 6! and the core 31.

Vibrations of the armature are damped by a dash pot which includes a plate support 89 having a series of openings through which bolts 32 extend. The bolts 82 pass through spacer sleeves 83 and enter tapped openings in the yoke "II. A cylinder 84 having an outwardly extending flange 85 is secured to the plate support 8i. Disposed centrally within the cylinder 84 and centrally is one end of a rod 86 which carries a disc 81 the periphery of which closely fits the annular wall of the cylinder 34. A flexible disc 88 which is at tached to flange 85 of cylinder 84 and to the rod 85 closes the cylinder 84. The space between the disc 88 and the back wall of the cylinder is completely filled with oil which is sealed in by a plain ring 89 and a corrugated ring 96 of spring metal secured together with the periphery of disc 88 against the flange 85 by a clamping ring 9i. Disc 83 is made of oil resisting material. such as neoprene.

The cylinder 85 is movable relative to the disc 81, the movement of the rod 85 being prevented by having the rod pass through the opening I3 in the arm I0 and having the other 'end attached to a self-aligning bearing comprising a cage 95 and a ball 95a. Cage 95 is attached to the stationary yoke 25 by a plate 96 secured by screws 91. The rod 86 is secured to the ball 95a by a nut 98 threaded on the end of rod 85 which passes through the ball.

As shown in the drawings the regulator thus far described includes compressible resistance or carbon discs pile 2d housed within the ceramic sleeve 23 located within the opening 22 of the housing 2i. One end of the carbon discs pile is engaged by a contactor Iili. The contactor has a spherical portion which is engaged by a contact I82 carried by a terminal screw I03 threadedly mounted in a plate I04. A lock nut I05 is provided to maintain the screw H33 fixed. The plate Hi l is provided with an aperture through which the rod 86 projects. The plate is insulatingly supported from the arm ID by insulating strips I05. The other end of the stack of carbon discs is engaged by a contactor I51 carried by an adjustable terminal screw I08. The terminal screw I08 is attached to a metallic internally threaded bushing IIiQ which is received by a plain opening in a contact support bracket i I0. In this instance the bushing has a reduced portion projecting through an opening in the contact support bracket I I0 and spun over the lower face thereof. The bracket Iii], rests upon the housing 25 but is insulated therefrom by an insulating strip III. The contact support bracket iIiJ is fixed to the housing 25 by screws H2 having threaded engagement with tapped holes provided in the housing.

The carbon pile 24 is normally placed under compression by adjustable tension springs II5 (Fig. 5) each having one end thereof hooked over a pin H6 attached to an ear III formed on the arm I5. The other end of each spring H5 is hooked over a pin H8 fixed to a stud H9. The studs II9 are of rectangular cross section and have a sliding fit in corresponding openings in sleeve I20, fixed to the yoke of bracket 25 in any suitable manner. Each stud is provided with a reduced threaded portion I2I which extends through the sleeve I20 and is in screw-threaded engagement with an adjusting nut I22. By turning the nuts 522 the initial tensions of the springs II5 are adjusted. The springs H5 urge the arm It counterclockwise (Fig. 2) relative to the hinge bracket flange 55 thereby causing the contact I02, carried by the plate I54, to bear against the contactor IIlI to compress the carbon pile 24 between the contacts [III and IE1.

The coil springs I I5 have given satisfactory results when regulation requires a limited movement of the regulator armature. If the condition of service is such as to require a relatively great movement of the armature, springs I23 of the type shown in Fig. 5A can be substituted for the coil springs I I5. The springs I23 are of flat stock and bent in and out as substantially shown in Fig. 5A. One end of the springs fit into a slot formed in the studs H9 and fixed therein by a rivet I24. The other end of the springs are fixed to the ears II? by rivets I25. The springs I23 are constructed so as to oppose magnetic pull by forces which increase substantially in proportion to the increase of magnetic pull as the gap between the armature and the core decreases. Springs I23 are of the same type as those disclosed in our application S. N. 646,675 filed February 9, 1946.

The yoke of the mounting bracket 25 is utilized to provide a mechanical support for a block I26 of insulating material for supporting headed terminal screws I21, I28 and I29. The terminal screws extend through counterbored openings provided by the block, the beads of the terminal screws being insulated from the yoke of bracket 25 by a sheet of insulation disposed between the block and the yoke. The block I25 is attached to the bracket 25 by screws I26a.

The regulator described heretofore can be used as a voltage regulator. Fig. 9 illustrates a current regulator I30, comprising a construction somewhat similar to the construction of the voltage regulator illustrated in Figs. 1 to '7. In Fig. 9, the core 31 supports a winding I32 of relatively heavy wire of relatively few turns. The yoke of the bracket supports an L-shaped block I of insulating material which is secured to the yoke by screws I36. One arm I31 of the block I35 supports terminals I38 and I39 while the other arm I40 supports terminal I 4|. One end of the winding I32 is connected to the terminal I38 while the other end of the winding I32 is connected to the terminal I39.

' The current regulator I 30 and the voltage regulator 20 are housed and supported within a metallic container a wall I of which is shown in Fig. 11. The housings 2| of the regulators project through openings I46 in wall I45 and are attached by screws I491: to a heat radiator I41 of aluminum or other good heat conducting material which has radiating fins I48, and which is attached to the wall I45 by screws I49, there being a heat insulating gasket I50 between the radiator and the box wall I45. The construction provides for dissipation of heat from the carbon piles.

For an understanding of the operation of the voltage regulator 20 and the current regulator I30 reference may be had to the circuit diagram Fig. 12 which shows one way in which the regulators may be-connected' in a circuit. A generator I whichis driven at Variable speed by a vehicle engine, is provided with an armature I6I brushes I62 and I63 and a field winding I64. The generator supplies current to the main circuit, indicated by heavy lines, across which circuit a storage battery I81 is connected to be charged by the generator. The brush I62 of the generator is connected with the terminal I38 by a lead I66. The terminal I38 is connected by a lead I61 to one end of the coil I32 of the current regulator I30. The other end of the coil I32 is connected with the terminal I39. A coil I1I of an actuating relay I12 is connected with a contact I84 of cutout relay I80. The relay I has an armature, not shown, carrying a strap I8I supporting contacts I82 and I83 normally separated from contacts I 84 and I85 and adapted respectively to engage them. Contact I85 is connected with a lead I86 with terminal of the battery I81. The strap I8I is connected by a lead I88 with a junction of magnet coils I89 and I90 of relay I80. The coil I89 of relatively few turns of low resistance is connected with a terminal I-9I of the actuating relay I12. The magnet coil I90 of a relatively large number of turns of relatively high resistance is connected with ground.

The actuating relay I12 has its coil I1I connected in series between the terminal I39 and the. contact I84 of the cutout relay. The armature I92 carries straps I93 and I94, separated by insulation. The strap I94 is grounded. The straps I93 and I94 carry, respectively, contacts I95 and I96. Contact I95 is normally separated from stationary contact I98. Both contacts I 9 1 and I98 are connected by leads to terminal I9I.

The operation of the actuating relay I12 and the cutout relay I80 is as follows: When generator is not. operating the upper contacts I96, I98 of the actuator relay I12 are closed and the lower contacts I95-491 are open. When the generator begins: to operate current will flow from brush I 62, wire I66, terminal I38, coil I32, terminal I39, coil I1I, contact I84, lead 2!, variable resistance 200, coil 40 to ground. When the voltage reaches a predetermined value the coil I1I will be energized sufiiciently to attract the armature I92 and close contacts I95, I91 and open contacts I96, I98. The closing of the contacts I95, I91 connects the cutout relay windings I89, I90 across the generator. The energization of the windings I89 and I90 attracts the armature IM to close contacts I82, I34 and contacts I83, I85 and complete a circuit between the generator and the battery I81. This circuit will remain completed although the generator voltage may not be suflicient for the coil I1I to hold the contact I95 in engagement with the contact I 91 providcd, however, the energization of coil I'II is not so weak that contact I96 touches the contact I98. Altho contact I95 may separate from contact I91 and render coil I89 ineffective, coil I90 still remains effective to hold the armature I8I down because coil I90 is still connected with the generator through contacts I82, I84.

When the generator voltage drops so low that it practically equals battery voltage, the battery coil I'llis not energized, and contact I96 engages contact I98, and coil I89 bucks coil I90 and the magnetism of relay I80 becomes too weak to hold the armature I8I down. Thus the armature is released by spring tension to separate the contacts I82, I84 and I83, I85. This prevents the battery from discharging :back through the generator.

The generator I80 has its shunt field winding I64 in series with terminal I65, carbon pile 24' of the current regulator I 30, the carbon pile 24 of the voltage regulator 20 and terminal I38, which is connected with brush I52 of the generator; The present system of regulation provides controlling the resistance of the various carbon piles therein. The resistance of the carbon pile 24 is controlled by a coil 40 responsive to variation in generator voltage, altho the voltage drop across the coil 48 is less than voltage across the generator brushes. The coil 40 surrounds a core'31 cooperating with the armature 60 attached to a bracket 10. Springs I I5 attached to the bracket 10 and the studs II9 urge the movable contactor I02, movable with the bracket, against the pile 24 toexert a predetermined initial pressure on the pile. As generator voltage increases, the coil 40 becomes more eifective to oppose the springs II5 and thereby reduce the pressure betweenthe carbon pile discs and thus increase the resistance and voltage drop across the pile 24.

The resistance of carbon pile 24 is controlled by a coil I32 responsive to charging current. The coil I32 surrounds the core I3! which cooperates with the armature 80 attached to the bracket 10 in a manner similar to that described by the voltage regulator. The springs II5 urge the movable contactor against the pile 24 to exert a predetermined initial pressure on the pile 24.

If the generator I60 is drawn by a vehiclepropelling engine whose speed does not vary greatly, the carbon pile regulators 20 and I30 will operate satisfactorily to control the generator output. However, if the generator is used with an engine whose speed varies over a relatively wide range, it is desirable to use an additional regulator 2I0 whose function is to variably ey-pass current around the shunt field winding I64 in order that the voltage regulator, in particular,

may be relieved of the duty of causing its pile 24 to place an exceptionally high resistance in the circuit of the shunt field winding to maintain the field strength within proper bounds at high generator speed.

Fig. 12 shows the by-passing regulator 2 I0 diagrammatically. It includes a carbon pile 2I3 which normally has high resistance since the discs, which are washer-like, are located between a fixed electrode 235, and a movable electrode 240,

the latter being operatively connected with a rod 234 attached to a lever 70 carrying an armature 60 as is the case of regulators 20 and I30. The springs H which urge the armature 68 away from the core 3'! also urge the electrode 240 away from the fixed electrode 235. As the voltage impressed on coil 25!] which surrounds core .31 increases, the resistance of the pile 2l3 decreases and therefore, its current carrying ability increases. Pile 2 i 3 is in shunt with the field wind-' ing I64. Coil 258 is in shunt with the piles 24 and 24' and is responsive to the difference between generator voltage and field voltage drop. As generator speed increases to its maximum value, coil 25!] becomes increasingly effective to decrease the resistance of pile 2 it which becomes increasingly effective to by-pass current from the field winding iG l. Voltage drop across the field is determined by the generator speed and output so the shunt regulator Zls does no have any effect on voltage drop in the field or in the main regulating carbon piles 24 and 2d. However, since the shunt regulator 2H1 does increase the current through the regulator piles, the resistance required of these piles is reduced by its action. This means that, in the higher speed range, the voltage drop across the piles 24 and 24 is secured without materially increasing the resistance in piles 24 and 24. Therefore piles 2d and 2d are relieved of the duty of maintaining the resistance within a relatively wide range.

At low speeds, the regulators 20 and I30 can perform :better without the icy-pass pile 2l3. Therefore relay 220 is provided. Its core 22! is surrounded by a coil 222 connected with armature support 223 and with pile 24. Support 223 is connected with pile 24'. Coil 222 is responsive to voltage drop across piles 24 and 24. When the voltage attains a certain value, the armature 224 moves down to close contacts 226 and 22'! thereby causing pile 2l3 to become effective" The construction of the housing 2!! (Fig. 9A) of the regulator 2"} is similar to that of housing 2i. In this instance the housing for the regulator 2m has a through opening to receive a ceramic tube 232. The stack of apertured carbon discs 2ft are housed within the tube 232. The stack of carbon discs surround the rod 235 (also Fig. 12) the ceramic tube 232 maintains the discs in aligned relation. The rod also extends through an apertured contactor 235 (electrode 235 in Fig. 12) fixed to the housing 23l by screws, not shown. One end of the rod 236 is provided with a reduced threaded portion which extends through a selfaligning bearing unit 23% carried by a plate 231 insulatlngly supported on an arm ill not shown in Fig. 9A. The other end of the rod has a head 238 which bears against a resilient dish-shaped washer 239 that bears against an apertured metallic Washer 248 (electrode Z lfl in Fig. 12) contacting one end of the carbon discs 253. The head 238 is provided with a recess to receive an insulating pad 2M. A cover 252 is secured to the housing by screws, not shown, and carries a stop screw 2453, which is adjustable to vary the movements of the rod 2%. A lock nut 245 is provided to secure the screw in the desired position of adjustment. The cover is provided with a side opening 2% through which a clip 24W attached to the head of the rod 22 may project. A clip 2&8 is attached to the contactor 235. The clip 2&8 and contact 235 are insulated from the housing by insulation. The clip 2&8 as shown is connected with a resistance unit 2&9 which is grounded.

From the foregoing it will be observed that the present invention has the distinct advantage that it permits the manufactur and assembly of standardized parts to form a main subassembly which may be used in making different electrical instruments for example, a voltage regulator, a current regulator, or a by-passing regulator. When it is desired to make certain of the regulators, a different coil is placed around the core and different terminal blocks are used without modification of the main subassembly. The present invention furthermore has the advantage that it permits the manufacture of different regulators which are of identical size to facilitate the assembly of different devices in containers of a certain size so that all or part of the regulators can be assembled in the case and connected without having same placed in a definite position. As an additional manufacturing advantage the apparatus of the invention dispenses with the necessity for special size regulators for special size containers that are constructed to receive a certain number of instruments.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A carbon pile regulator comprising, a plurality of-juxtaposed carbon disc forming a stack; a housing enclosing the stack; a U-shaped magtizable frame supported by the housing and providing pole faces; a core surrounded by a winding supported by the frame; a U-shaped bracket adjustably supported by the frame adjacent and parallel to the core; a blade hinge adjustably secured at one end to the bracket; an armature attached to the other end of the hinge; and spring for opposing movement of the armature toward the core by magnetic force said spring having one end connected to adjustable means carried by the frame and having the other end connected with a part associated with the armature.

2. A carbon pile regulator comprising, a plurality of juxtaposed carbon disc forming a stack; a housing enclosing the stack; a U-shaped magnetizabie frame supported by the housing and providing pole faces; a core surrounded by a winding supported by the frame; a bracket adjustably supported by the frame adjacent and parallel to the core; a blade spring hinge adjustably secured at one end to the bracket; an armature attached to the hinge; and a spring extending parallel to the stack and located between the housing and the U-shaped frame for opposing movement of the armature toward the core by magnetic force said spring having one end connected with the frame and having the other end connected with a part carried by the armature.

. 3. A carbon pile regulator comprising; a stack of discs of resistance material; a housing enclosing the stack; an electrode engaging one end of the stack and fixed relative to one end of the housing; an electrode engaging the other end of the stack and movable relative to the other end of the housing; a U -shaped magnetizable frame supported by the frame; an electromagnet supported by the frame; a bracket adjustably supported by the frame; a temperature responsive leaf spring hinge adjustably attached to the bracket; an armature attached to the hinge and cooperating with the electromagnet; spring means for opposing movement of the armature toward the electromagnet; a force transmitting device under con- 9 trol .of :the spring :force .and ;the magnetic force to move the movable electrode for effecting the resistance f the stack.

-:4. \A carbon'pileregulator comprising, a fixed housing; a stack ;of :carbon discs located within the housing; :an .aad-iustable electrode supported bythe housing andengagingone end of the stack; armovable electrode:engagingthe-other end of the stack; a vmagnetizable frame supported by the housing-and providing polefaces; an electromagnetisupported-rby the frame ;.an adjustable bracket supported by the frame; ;a leaf spring hinge .adjustablysupported atone end on the bracket; an armature cooperating with the electromagnet and attached to therotherend of the leaf spring; an arm comprising-side members :attached to the armature and carrying a plate attached to the movable electrodeisaid side member having openings ,toexposeitheadjustable means between the bracket and frame; means for insulating the plate from the arm; and spring means connected with the .frametand theiar m for urging the plate and the arm in one direction to move the movable electrode in a direction to compress the stack and opposing movementof the armature 'toward the electromagnet.

5. A carbon pile regulator comprising, a housing; a stack of discs of resistance material located within thehousing; a magnetizable frame supported by the housing and providing pole faces; a core surrounded by a Winding supported by the frame; a hinge bracket adjustably supported by the frame adjacent and parallel to the core; a leaf spring hinge adjustably supported at one end on the bracket; an armature secured to the leaf spring means for opposing movement of the armature toward the core by magnetic force; a force transmitting device under control of the spring means and the magnetic force; and means operated by the force transmitting device for effecting the resistance of the stack.

6. A carbon pile regulator comprising, a housing; a stack of discs of resistance material located within the housing; a magnetizable frame supported by the housing and providing pole faces; a core surrouded by a winding supported by the frame; a hinge bracket adjustably supported by the frame adjacent and parallel to the core; a leaf spring hinge adjustably connected to the bracket; an armature fixed to the leaf spring, spring means for opposing movement of the armature toward the core by magnetic force; a force transmitting device attached to the armature and under control of the spring means and the magnetic force; and means for effecting the resistance of the stack, said means including an electrode operated by said device and applying pressure to the end of the stack adjacent to said device, the other end of the stack remote from said device being engaged by a relatively fixed electrode supported by the housing.

7. A carbon pile regulator comprising, a housing; a stack of discs of resistance material located within the housing; a magnetizable frame sup ported by the housing and providing pole faces; a core surrounded by a Winding supported by the frame; a U-shaped bracket supported by the frame adjacent and parallel to the core; a leaf spring adjustably on the bracket; an armature carried by the leaf spring, spring means for opposing movement of the armature toward the core by magnetic force; a force transmitting device attached at one end to the armature and under control of the spring force and the magnetic force; and means for effecting the resistance of '10 thestack, said-means including an electrode operated by said device and applying pressure to the end of the stack, the other end of the stack being engaged by an electrode adjustably supported on the housing.

8. A carbon pile regulator comprising juxtaposed carbon discs forming a stack; a housing enclosing the stack; an electrode engaging one end of the stack and fixed relative to one end of the housing; an electrode engaging the other end of the stack and movable relative to the other end of the housing; a U-shaped magnetizable frame supported by the housing and providing pole faces; a U-shaped bracket supported by frame; a fiat spring hinge adjustably attached at one end to the bracket; an electromagnet supported by the frame; an armature cooperating with the electromagnet and attached to the other of the hinge; a U-shaped arm having its side branches attached to the armature and having the yoke connected with the movable electrode; 'a coil spring disposed between the frame and the housing and having one end connected to the yoke of the arm and having the other end attached to an adjustable vpart supported by a fixed part of the regulator, said spring opposing the movement of the armature toward the electromagnet when energized and also operating to urge constantly the movable electrode against the stack and thereby regulate the resistance of the stack.

9. A carbon pile regulator according to claim 8 wherein the spring comprises an elongated strip of spring metal having a plurality of corrugations intermediate its ends.

10. A carbon pile regulator comprising, a housing; a stack of discs of resistance material located within the housing; an adjustable electrode supported by one end of the housing and engaging one end of the stack; a movable electrode engaging the other end of the stack; a U-shaped magnetizable frame supported by the housing and providing pole faces; an electromagnet supported by the frame; an adjustable bracket supported by the frame; an armature cooperating with the electromagnet; a leaf spring resiliently supporting the armature from the bracket and capable of a justment relative to said bracket; coil spring means for opposing movement of the armature toward the electromagnet upon energization thereof; an arm having side plates parallel. respectively to the branches of the U-shaped frame and attached to the armature and having a web connecting the side plates and attached to the coil spring means; and means movable with the arm for operating the movable electrode for effecting the resistance of the stack.

11. A carbon pile regulator comprising, a plurality of juxtaposed carbon discs forming a stack; a housing enclosing the stack; a U-shaped support carried by the housing; a U-shaped magnetizable frame supported by the support and providing pole faces with the yoke of the frame adjacent the housing but spaced therefrom; a core surrounded by a winding supported by the yoke of the frame; a U-shaped bracket adjustably supported on the frame; a leaf spring adjustably supported at one end on the bracket; an armature carried at the other end of the leaf spring; a U -shaped arm attached to the armature and having side brackets straddling the bracket, said branches having openings exposing the adjusting means between the bracket and the frame to permit adjustment of brackets relative to the frame; and spring means for opposing the movement of the armature toward the core by magnetic force, said spring means being located between the housin and the yoke of the frame and having one end connected with adjustable means carried by the support and having the other end connected with a part of the arm; means for efiecting the resistance of the stack, said means including an electrode carried by the arm and engaging one end of the stack, the other end of the stack being engageable by an electrode adjustably supported by the housing and means carried by the yoke of the arm for dampening the movements of the armature.

12. A carbon pile regulator comprising, a hous ing; a stack of resistance discs movable within the housing; a U-shaped support including a yoke and parallel branches, said branches having foot portions by means of which the support is rigidly fixed to the housing; a U-shaped, magnetizable frame including a yoke portion and parallel arms providing pole faces, said arms being nested between the branches and secured thereto with the yoke of the frame spaced from the housing; a core surrounded by a winding attached to the yoke of the frame and positioned intermediate the arms of the frame; a U-shape bracket including a yoke and parallel arms, said arms straddling the branches of the support and adjustably supported thereon; a leaf spring having one end adjustably aflixed to the yoke of the bracket for holding the leaf spring in a cantilever condition 12 relative to the yoke, an armature secured to the leaf spring and spaced by an air gap from the end of the pole faces; a U-shaped arm including parallel side portions straddling the bracket and having extending portions by means of which the arm is rigidly fixed to the armature, a coil spring for opposing movement of the armature toward the core by magnetic force, said spring being located between the housing and the yoke of the support and having one end connected to adjustable means carried by the frame and having the other end connected to he yoke of the arm; and means for efiecting the resistance of the stack, said means including an electrode movable with the arm, the other end of the stack being engaged by an adjustable electrode supported by the housing.

WILLIAM J. RADY. LYMAN A. RICE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,259,172 Turbayne Mar. 12, 1918 1,291,597 Moskowitz Jan. 14, 1919 1,438,934 Creveling Dec. 12, 1922 2,394,753 Crotch Feb. 12, 1946 2,400,136 Rady May 14, 1946 

